They are called “indefinite” simply because they do not indicate the exact object, being, or place to which they refer.
- Singular: another, anybody, anyone, anything, each, either, everybody, everyone, everything, little, much, neither, nobody, no one, nothing, one, other, somebody, someone, something
- Plural: both, few, fewer, many, others, several
- Singular or Plural: all, any, more, most, none, some, such
Singular indefinite pronouns take singular verbs or singular personal pronouns.
Incorrect: Each of the members have one vote.
Correct: Each of the members has one vote.
(The subject "each" is singular, use "has".)
Incorrect: One of the girls gave up their seat.
Correct: One of the girls gave up her seat.
("Her" refers to "one", which is singular.)
Plural indefinite pronouns take plural verbs or plural personal pronouns.
Incorrect: A few of the justices was voicing his opposition.
Correct: A few of the justices were voicing their opposition.
("Few" is plural, so are "were" and "their".)
For indefinite pronouns that can be singular or plural, it depends on what the indefinite pronoun refers to.
Incorrect: All of them is experts in their chosen field.
Correct: All of them are experts in their chosen field.
("All" refers to "them", which is plural.)
Incorrect: All of the newspaper were soaked.
Correct: All of the newspaper was soaked.
(Here "all" refers to "newspaper", which is singular.)